2002 JEEP GRAND CHEROKEE turn signal fuse

ergize the combination flasher in response to mes-
sage inputs received over the Programmable
Communications Interface (PCI) data bus network.
The BCM can energize the combination flasher when
the VTSS is requested.
Vehicles equipped with the optional Electronic
Vehicle Information Center (EVIC) use turn signal
status messages received from the Electro-Mechani-
cal Instrument Cluster (EMIC) and distance mes-
sages received from the Powertrain Control Module
(PCM) over the PCI data bus to determine when the
Turn Signal On warning should be activated. The
EMIC receives hard wired inputs from the combina-
tion flasher to operate the turn signal indicators,
then sends the proper turn signal status message to
the EVIC. If a turn signal is left on for more than
about 1.6 kilometers (1 mile) of driving distance, the
EVIC will display a visual ªTurn Signal Onº message
and will send a request to the BCM over the PCI
data bus to notify the vehicle operator.
During both the turn signal and the hazard warn-
ing operation, if the exterior lamps are turned Off,
the front park/turn signal lamps and the front side
marker lamps will flash in unison. If the exterior
lamps are turned On, the front park/turn signal
lamps and the front side marker lamps will flash
alternately. Refer to the owner's manual.
DIAGNOSIS AND TESTING - TURN SIGNAL &
HAZARD WARNING SYSTEMS
When diagnosing the turn signal and hazard warn-
ing circuits, remember that high generator output
can burn out bulbs rapidly and repeatedly. If this is a
concern on the vehicle being diagnosed, test the
charging system as required.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE AIRBAG SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE AIRBAG SYS-
TEM CAPACITOR TO DISCHARGE BEFORE PER-
FORMING FURTHER DIAGNOSIS OR SERVICE. THIS
IS THE ONLY SURE WAY TO DISABLE THE AIRBAG
SYSTEM. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Turn the ignition switch to the On position.
Actuate the turn signal switch or the hazard warning
switch. Observe the turn signal indicator lamp(s) in
the instrument cluster. If the flash rate is very high,
check for a turn signal bulb that is not lit or is verydimly lit. Repair the circuits to that lamp or replace
the faulty bulb, as required. If the turn signal indi-
cator(s) fail to light, go to Step 2.
(2) Turn the ignition switch to the Off position.
Check the ignition run fuse and the flasher fuse in
the Junction Block (JB). If OK, go to Step 3. If not
OK, repair the shorted circuit or component as
required and replace the faulty fuse(s).
(3) Check for battery voltage at the flasher fuse in
the JB. If OK, go to Step 4. If not OK, repair the
open fused B(+) circuit between the JB and the
Power Distribution Center (PDC).
(4) Turn the ignition switch to the On position.
Check for battery voltage at the ignition run fuse in
the JB. If OK, go to Step 5. If not OK, repair the
open fused ignition switch output (run) circuit
between the JB and the ignition switch.
(5) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the combination flasher from the JB and
replace it with a known good unit. Reconnect the bat-
tery negative cable. Test the operation of the turn
signal and hazard warning systems. If OK, discard
the faulty combination flasher. If not OK, remove the
test flasher and go to Step 6.
(6) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run) circuit cavity in the JB for the combina-
tion flasher. If OK, go to Step 7. If not OK, repair the
open fused ignition switch output (run) circuit
between the combination flasher and the ignition run
fuse in the JB.
(7) Turn the ignition switch to the Off position.
Check for battery voltage at the B(+) circuit of the JB
for the combination flasher. If OK, go to Step 8. If
not OK, repair the open B(+) circuit between the
combination flasher and the flasher fuse in the JB.
(8) Disconnect and isolate the battery negative
cable. Disconnect the instrument panel wire harness
connector for the turn signal and hazard warning
switches from the multi-function switch connector.
Check for continuity between the ground circuit of
the instrument panel wire harness connector for the
left multi-function switch and a good ground. There
should be continuity. If OK, go to Step 9. If not OK,
repair the open ground circuit.
(9) Check for continuity between the hazard switch
sense circuit of the instrument panel wire harness
connector for the multi-function switch and a good
ground. There should be no continuity. If OK, go to
Step 10. If not OK, repair the shorted hazard switch
sense circuit between the multi-function switch and
the combination flasher.
(10) Check for continuity between the hazard
switch sense circuit of the JB for the combination
flasher and the instrument panel wire harness con-
WJLAMPS/LIGHTING - EXTERIOR 8L - 3
LAMPS/LIGHTING - EXTERIOR (Continued)

INSTALLATION - CHMSL
(1) Connect the wire harness connector.
(2) Position the CHMSL on liftgate.
(3) Install the screws attaching the CHMSL to the
liftgate.
COMBINATION FLASHER
DESCRIPTION
The combination flasher is located in the Junction
Block (JB) (Fig. 6). The JB is located underneath the
driver side of the instrument panel outboard of the
steering column. The combination flasher is a smart
relay that functions as both the turn signal system
and the hazard warning system flasher. The combi-
nation flasher contains active electronic Integrated
Circuitry (IC) elements. This flasher is designed to
handle the current flow requirements of the factory-
installed lighting. If supplemental lighting is added
to the turn signal lamp circuits, such as when towing
a trailer with lights, the combination flasher will
automatically try to compensate to keep the flash
rate the same.The combination flasher has nine blade-type termi-
nals that connect it to the vehicle electrical system.
Refer to the appropriate wiring information.
Because of the active electronic elements within
the combination flasher, it cannot be tested with con-
ventional automotive electrical test equipment. If the
combination flasher is believed to be faulty, test the
turn signal system and hazard warning system cir-
cuits.(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING
- EXTERIOR - DIAGNOSIS AND TESTING - TURN
SIGNAL & HAZARD WARNING SYSTEM). The com-
bination flasher cannot be repaired or adjusted and,
if faulty or damaged, it must be replaced.
OPERATION
The combination flasher controls the following
inputs and outputs: B(+), fused ignition switch out-
put, left turn switch sense, right turn switch sense,
hazard switch sense, left front turn signal circuit,
right front turn signal circuit, left rear turn signal
circuit and right rear turn signal circuit. Constant
battery voltage is supplied to the flasher so that it
can perform the hazard warning function, and igni-
tion switched battery voltage is supplied for the turn
signal function. However, when the flasher is idle no
current is drawn through the module. The unit does
not become active until it is provided a signal ground
from the turn signal switch, hazard warning switch
or the Body Control Module (BCM).
The IC within the combination flasher (Fig. 7) con-
tains the logic that controls the flasher operation and
the flash rate. When a bulb is burnt out, or when a
circuit for a lamp is open, the turn signal flash rate
will increase. However, an open lamp circuit or burnt
out bulb does not change the hazard warning flash
rate.
Fig. 6 Combination Flasher
1 - COMBINATION FLASHER
2 - JUNCTION BLOCK
WJLAMPS/LIGHTING - EXTERIOR 8L - 7
CENTER HIGH MOUNTED STOP LAMP (Continued)

COMBINATION FLASHER CIRCUITS
CAVITY CIRCUIT FUNCTION
1 L25 Fused B(+)
2 L61 Left Front Turn Signal
3 L60 Right Front Turn Signal
4 L63 Left Rear Turn Signal
5 L62 Right Rear Turn Signal
6 F22 Fused Ignition Switch Output
7 L305 Left Turn Switch Sense
8 L302 Right Turn Switch Sense
9 L91 Hazard Switch Sense
Fig. 7 Combination Flasher
8L - 8 LAMPS/LIGHTING - EXTERIORWJ
COMBINATION FLASHER (Continued)

See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the power lock system.
OPERATION - REMOTE KEYLESS ENTRY
SYSTEM
The Passenger Door Module (PDM) contains the
RKE system control logic and the RKE receiver.
When the RKE receiver recognizes a Lock, Unlock or
Panic message from a valid RKE transmitter, the
RKE receiver provides that input to the PDM. The
PDM circuitry and programming responds by sending
the proper messages to the other electronic modules
over the Programmable Communications Interface
(PCI) data bus.
When an RKE lock message is received, the doors
and the liftgate lock, the interior lighting fades to off,
the horn chirps (if this feature is enabled), the exte-
rior lamps flash (if this feature is enabled) and, if the
vehicle is so equipped, the Vehicle Theft Security
System (VTSS) is armed. When an RKE unlock mes-
sage is received, the driver side front door (or all
doors and the liftgate if this feature is enabled)
unlock, the interior lighting is turned on and, if the
vehicle is so equipped, the VTSS is disarmed. If the
vehicle is equipped with the Memory System and the
RKE Linked to Memory feature is enabled, the RKE
unlock message also recalls the driver seat, outside
mirror and radio settings assigned to the RKE trans-
mitter that sent the unlock signal.
When an RKE panic message is received, it causes
the exterior lamps (including the headlights) to flash,
and the horn to pulse for about three minutes, or
until a second panic message is received. A vehicle
speed of about 24 kilometers-per-hour (15 miles-per-
hour) will also cancel the panic event.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the RKE system.
OPERATION - LIFTGATE FLIP-UP GLASS
POWER RELEASE SYSTEM
When the liftgate mounted flip-up glass release
switch is depressed, battery current is directed to the
electric release motor that is integral to the flip-up
glass latch located inside the liftgate. When the
release motor is energized the latch releases and the
flip-up glass can be opened. A liftgate flip-up glass
limit switch is integral to the liftgate latch actuator
mechanism. The limit switch automatically enables
or disables the liftgate flip-up glass power release cir-
cuitry, depending upon the position of the liftgate
latch lock mechanism. When the liftgate latch is
unlocked, the limit switch closes and battery current
is available at the release switch. When the liftgatelatch is locked , the limit switch opens, and the
release switch is disabled.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the liftgate flip-up glass power release system.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - POWER LOCK
SYSTEM
Following are tests that will help to diagnose the
hard wired components and circuits of the power lock
system. However, these tests may not prove conclu-
sive in the diagnosis of this system. In order to
obtain conclusive testing of the power lock system,
the Programmable Communications Interface (PCI)
data bus network and all of the electronic modules
that provide inputs to, or receive outputs from the
power lock system components must be checked.
The most reliable, efficient, and accurate means to
diagnose the power lock system requires the use of a
DRBIIItscan tool and the proper Diagnostic Proce-
dures manual. The DRBIIItscan tool can provide
confirmation that the PCI data bus is functional, that
all of the electronic modules are sending and receiv-
ing the proper messages on the PCI data bus, and
that the power lock motors are being sent the proper
hard wired outputs by the door modules for them to
perform their power lock system functions.
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
PRELIMINARY DIAGNOSIS
As a preliminary diagnosis for the power lock sys-
tem, note the system operation while you actuate
both the Lock and Unlock functions with the power
lock switches and with the Remote Keyless Entry
(RKE) transmitter. Then, proceed as follows:
²If the entire power lock system fails to function
with either the power lock switches or the RKE
transmitter, check the fused B(+) fuse in the Power
Distribution Center. If the fuse is OK, proceed to
diagnosis of the door modules. (Refer to 8 - ELEC-
TRICAL/ELECTRONIC CONTROL MODULES/
DOOR MODULE - DIAGNOSIS AND TESTING).
²If the power lock system functions with both
power lock switches, but not with the RKE transmit-
ter, proceed to diagnosis of the Remote Keyless Entry
(RKE) system. (Refer to 8 - ELECTRICAL/POWER
LOCKS - DIAGNOSIS AND TESTING - REMOTE
KEYLESS ENTRY SYSTEM).
WJPOWER LOCKS 8N - 5
POWER LOCKS (Continued)

²If the power lock system functions with the RKE
transmitter, but not with one or both power lock
switches, proceed to diagnosis of the door modules.
(Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/DOOR MODULE - DIAGNOSIS
AND TESTING).
²If the driver side power lock switch operates
only the driver side front door power lock motor, but
all other power lock motors operate with the passen-
ger side power lock switch or the RKE transmitter,
use a DRBIIItscan tool and the appropriate diagnos-
tic information to diagnose the Programmable Com-
munications Interface (PCI) data bus.
²If only one power lock motor fails to operate
with both power lock switches and the RKE trans-
mitter, proceed to diagnosis of the power lock motor.
(Refer to 8 - ELECTRICAL/POWER LOCKS/POWER
LOCK MOTOR - DIAGNOSIS AND TESTING).
DIAGNOSIS AND TESTING - REMOTE KEYLESS
ENTRY SYSTEM
Following are tests that will help to diagnose the
Remote Keyless Entry (RKE) system. However, these
tests may not prove conclusive in the diagnosis of
this system. In order to obtain conclusive testing of
the RKE system, the Programmable Communications
Interface (PCI) data bus network and all of the elec-
tronic modules that provide inputs to, or receive out-
puts from the RKE system components must be
checked.
The most reliable, efficient, and accurate means to
diagnose the RKE system requires the use of a
DRBIIItscan tool and the appropriate diagnostic
information. The DRBIIItscan tool can provide con-
firmation that the PCI data bus is functional, that all
of the electronic modules are sending and receiving
the proper messages on the PCI data bus, and that
the RKE receiver is being sent the proper radio fre-
quency signals by the RKE transmitters to perform
its RKE system functions.
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
PRELIMINARY DIAGNOSIS
As a preliminary diagnosis for the RKE system,
note the system operation while you perform both the
Lock and Unlock functions with the power lock
switches and with the Remote Keyless Entry (RKE)
transmitter. Then, proceed as follows:
²If the entire power lock system fails to function
with either the power lock switches or the RKE
transmitter, check the fused B(+) fuse in the PowerDistribution Center. If the fuse is OK, proceed to the
diagnosis for the door modules. (Refer to 8 - ELEC-
TRICAL/ELECTRONIC CONTROL MODULES/
DOOR MODULE - DIAGNOSIS AND TESTING).
²If the power lock system functions with both
power lock switches, but not with the RKE transmit-
ter, proceed to the diagnosis for the RKE transmitter.
(Refer to 8 - ELECTRICAL/POWER LOCKS/RE-
MOTE KEYLESS ENTRY TRANSMITTER - DIAG-
NOSIS AND TESTING).
²If the driver side power lock switch operates
only the driver side front door power lock motor, but
all other power lock motors operate with the passen-
ger side power lock switch or the RKE transmitter,
use a DRBIIItscan tool and the appropriate diagnos-
tic information to diagnose the Programmable Com-
munications Interface (PCI) data bus.
If the problem being diagnosed involves only the
Sound Horn on Lock or the Flash Lights with Locks
features, be certain that these programmable fea-
tures are enabled. If the features are enabled and the
service horn and turn signals still operate, the Body
Control Module (BCM) and the PCI data bus must be
tested. For diagnosis of the BCM or the PCI data
bus, the use of a DRBIII scan tool and the appropri-
ate diagnostic information are required.
DIAGNOSIS AND TESTING - LIFTGATE FLIP-UP
GLASS POWER RELEASE SYSTEM
Refer to the appropriate wiring information. The
wiring information includes wiring diagrams, proper
wire and connector repair procedures, details of wire
harness routing and retention, connector pin-out
information and location views for the various wire
harness connectors, splices and grounds.
(1) Check the fused B(+) fuse in the Junction
Block (JB). If OK, go to Step 2. If not OK, repair the
shorted circuit or component as required and replace
the faulty fuse.
(2) Check for battery voltage at the fused B(+) fuse
in the JB. If OK, go to Step 3. If not OK, repair the
open fused B(+) circuit to the Power Distribution
Center (PDC) as required.
(3) Disconnect the liftgate wire harness connector
for the liftgate lock motor and flip-up glass limit
switch from the motor and switch connector recepta-
cle. Check for battery voltage at the fused B(+) cir-
cuit cavity of the liftgate wire harness connector for
the liftgate lock motor and flip-up glass limit switch.
If OK, go to Step 4. If not OK, repair the open fused
B(+) circuit between the liftgate lock motor and
flip-up glass limit switch and the JB as required.
(4) Check for continuity between the two liftgate
flip-up glass limit switch terminals. There should be
continuity with the liftgate latch unlocked, and no
continuity with the latch locked. If OK, go to Step 5.
8N - 6 POWER LOCKSWJ
POWER LOCKS (Continued)

DESCRIPTION - OUTSIDE REAR VIEW MIRROR
An automatic dimming outside rear view mirror is
an available factory-installed option for the driver
side of the vehicle, if the vehicle is also equipped
with the automatic day/night inside rear view mirror.
The automatic dimming outside mirror is completely
controlled by the circuitry of the automatic day/night
inside rear view mirror. The automatic dimming out-
side mirror will automatically change the reflectance
of the driver side outside rear view mirror to protect
the driver from the unwanted headlight glare of
trailing vehicles while driving at night. The auto-
matic dimming outside mirror will only operate when
the ignition switch is in the On position.
The automatic dimming outside mirror sensitivity
cannot be repaired or adjusted. If any component of
this unit is faulty or damaged, the entire automatic
dimming outside mirror unit must be replaced. (Refer
to 8 - ELECTRICAL/POWER MIRRORS/SIDEVIEW
MIRROR - DIAGNOSIS AND TESTING). Refer to
the appropriate wiring information. The wiring infor-
mation includes wiring diagrams, proper wire and
connector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
OPERATION
OPERATION - REAR VIEW MIRROR
The automatic day/night mirror switch allows the
driver a manual control of whether the automatic
dimming feature is operational. This switch is a
momentary rocker-type switch located on the lower
rear-facing surface of the mirror housing. When Auto
is selected, a Light-Emitting Diode (LED) on the mir-
ror housing just to the right of the switch illuminates
to indicate that automatic day/night mirror is turned
on. When Off is selected, the LED is turned off. The
mirror also senses the backup lamp circuit, and will
automatically disable its self-dimming feature when-
ever the transmission gear selector is in the Reverse
position.
A thin layer of electrochromatic material between
two pieces of conductive glass make up the face of
the mirror. Two photocell sensors are used to monitor
light levels and adjust the reflectance of the mirror.
The ambient photocell sensor faces forward, to detect
the outside light levels. The headlamp sensor is
located on the mirror housing just to the left of the
switch and facing rearward, to detect the light level
received at the rear window side of the mirror. When
the difference between the two light levels becomes
too great (the light level received at the rear of themirror is much higher than that at the front of the
mirror), the mirror begins to darken.
On models with an optional driver side automatic
dimming outside mirror, the signal to control the
dimming of that mirror is generated by the auto-
matic day/night inside rear view mirror circuitry.
That signal is then delivered to the driver side out-
side rear view mirror on a hard wired circuit.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the automatic day/night mirror system.
OPERATION - OUTSIDE REAR VIEW MIRROR
The automatic dimming outside mirror is operated
by the same controls and circuitry as the automatic
day/night mirror. When the automatic day/night mir-
ror is turned on or off, the automatic dimming out-
side mirror is likewise turned on or off. Like in the
automatic day/night mirror, a thin layer of electro-
chromatic material between two pieces of conductive
glass make up the face of the automatic dimming
outside mirror. However, the signal to control the
dimming of the outside mirror is generated by the
automatic day/night inside rear view mirror circuitry.
See the owner's manual in the vehicle glove box for
more information on the features, use and operation
of the automatic dimming outside mirror.
DIAGNOSIS AND TESTING - AUTOMATIC DAY /
NIGHT MIRROR
For complete circuit diagrams, refer to the appro-
priate wiring information. The wiring information
includes wiring diagrams, proper wire and connector
repair procedures, details of wire harness routing
and retention, connector pin-out information and
location views for the various wire harness connec-
tors, splices and grounds.
(1) Check the fused ignition switch output (run/
start) fuse in the junction block. If OK, go to Step 2.
If not OK, repair the shorted circuit or component as
required and replace the faulty fuse.
(2) Turn the ignition switch to the On position.
Check for battery voltage at the fused ignition switch
output (run/start) fuse in the junction block. If OK,
go to Step 3. If not OK, repair the open fused ignition
switch output (run/start) circuit to the ignition switch
as required.
(3) Disconnect the overhead wire harness connec-
tor from the automatic day/night mirror connector
receptacle. Check for battery voltage at the fused
ignition switch output (run/start) circuit cavity of the
overhead wire harness connector for the automatic
day/night mirror. If OK, go to Step 4. If not OK,
repair the open fused ignition switch output (run/
start) circuit to the fuse in the junction block as
required.
WJPOWER MIRRORS 8N - 13
AUTOMATIC DAY/NIGHT MIRROR (Continued)

The ACM microprocessor continuously monitors all
of the supplemental restraint system electrical cir-
cuits to determine the system readiness. If the ACM
detects a monitored system fault, it sets an active
and stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the EMIC over the PCI data
bus to turn on the airbag indicator. An active fault
only remains for the duration of the fault or in some
cases the duration of the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the ACM. For some DTCs, if a fault
does not recur for a number of ignition cycles, the
ACM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.
The ACM receives battery current through two cir-
cuits, on a fused ignition switch output (run) circuit
through a fuse in the Junction Block (JB), and on a
fused ignition switch output (start-run) circuit
through a second fuse in the JB. The ACM is
grounded through a ground circuit and take out of
the instrument panel floor wire harness. This take
out has a single eyelet terminal connector secured by
a nut to a ground stud located behind the ACM
mount on the floor panel transmission tunnel. These
connections allow the ACM to be operational when-
ever the ignition switch is in the Start or On posi-
tions. The ACM also contains an energy-storage
capacitor. When the ignition switch is in the Start or
On positions, this capacitor is continually being
charged with enough electrical energy to deploy the
airbags for up to one second following a battery dis-
connect or failure. The purpose of the capacitor is to
provide backup supplemental restraint system pro-
tection in case there is a loss of battery current sup-
ply to the ACM during an impact.
Two sensors are contained within the ACM, an
electronic impact sensor and a safing sensor. The
ACM also monitors inputs from two remote front
impact sensors located on brackets on the inboard
sides of the right and left vertical members of the
radiator support near the front of the vehicle. The
electronic impact sensors are accelerometers that
sense the rate of vehicle deceleration, which provide
verification of the direction and severity of an
impact. On models equipped with optional side cur-
tain airbags, the ACM also monitors inputs from two
remote side impact sensors located near the base of
both the left and right inner B-pillars to control the
deployment of the side curtain airbag units.
The safing sensor is an electronic accelerometer
sensor within the ACM that provides an additional
logic input to the ACM microprocessor. The safingsensor is used to verify the need for an airbag
deployment by detecting impact energy of a lesser
magnitude than that of the primary electronic impact
sensors, and must exceed a safing threshold in order
for the airbags to deploy. The ACM also monitors a
Hall effect-type seat belt switch located in the buckle
of each front seat belt to determine whether the seat-
belts are buckled, and provides an input to the EMIC
over the PCI data bus to control the seatbelt indica-
tor operation based upon the status of the driver side
front seat belt switch. Vehicles with the optional side
curtain airbags feature a second safing sensor within
the ACM to provide confirmation to the ACM of side
impact forces. This second safing sensor is a bi-direc-
tional unit that detects impact forces from either side
of the vehicle.
Pre-programmed decision algorithms in the ACM
microprocessor determine when the deceleration rate
as signaled by the impact sensors and the safing sen-
sors indicate an impact that is severe enough to
require supplemental restraint system protection.
The ACM also determines the level of front airbag
deployment force required for each front seating posi-
tion based upon the status of the two seat belt switch
inputs and the severity of the monitored impact.
When the programmed conditions are met, the ACM
sends the proper electrical signals to deploy the mul-
tistage dual front airbags at the programmed force
levels, and to deploy either side curtain airbag.
The hard wired inputs and outputs for the ACM
may be diagnosed and tested using conventional
diagnostic tools and procedures. However, conven-
tional diagnostic methods will not prove conclusive in
the diagnosis of the ACM, the PCI data bus network,
or the electronic message inputs to and outputs from
the ACM. The most reliable, efficient, and accurate
means to diagnose the ACM, the PCI data bus net-
work, and the electronic message inputs to and out-
puts from the ACM requires the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation.
REMOVAL
Two different Airbag Control Modules (ACM) are
available for this vehicle. For vehicles equipped with
the optional side curtain airbags, both ACM connec-
tor receptacles are black in color and the ACM con-
tains a second bi-directional safing sensor for the
side airbags. For vehicles not equipped with the
optional side curtain airbags, the ACM connector
receptacles are gray.
8O - 10 RESTRAINTSWJ
AIRBAG CONTROL MODULE (Continued)

OPERATION
The multistage driver airbag is deployed by electri-
cal signals generated by the Airbag Control Module
(ACM) through the driver airbag squib 1 and squib 2
circuits to the two initiators in the airbag inflator. By
using two initiators, the airbag can be deployed at
multiple levels of force. The force level is controlled
by the ACM to suit the monitored impact conditions
by providing one of four delay intervals between the
electrical signals provided to the two initiators. The
longer the delay between these signals, the less force-
fully the airbag will deploy. When the ACM sends the
proper electrical signals to each initiator, the electri-
cal energy generates enough heat to initiate a small
pyrotechnic charge which, in turn ignites chemical
pellets within the inflator. Once ignited, these chem-
ical pellets burn rapidly and produce a large quantity
of nitrogen gas. The inflator is sealed to the back of
the airbag housing and a diffuser in the inflator
directs all of the nitrogen gas into the airbag cush-
ion, causing the cushion to inflate. As the cushion
inflates, the driver airbag trim cover will split at pre-
determined breakout lines, then fold back out of the
way along with the horn switch and tray unit. Fol-
lowing an airbag deployment, the airbag cushion
quickly deflates by venting the nitrogen gas towards
the instrument panel through vent holes within the
fabric used to construct the back (steering wheel
side) panel of the airbag cushion.
Some of the chemicals used to create the nitrogen
gas may be considered hazardous while in their solid
state before they are burned, but they are securely
sealed within the airbag inflator. Typically, both ini-
tiators are used and all potentially hazardous chem-
icals are burned during an airbag deployment event.
However, it is possible for only one initiator to be
used during a deployment due to an airbag system
fault; therefore, it is necessary to always confirm
that both initiators have been used in order to avoid
the improper disposal of potentially live pyrotechnic
or hazardous materials. (Refer to 8 - ELECTRICAL/
RESTRAINTS - STANDARD PROCEDURE - SER-
VICE AFTER A SUPPLEMENTAL RESTRAINT
DEPLOYMENT). The nitrogen gas that is produced
when the chemicals are burned is harmless. How-
ever, a small amount of residue from the burned
chemicals may cause some temporary discomfort if it
contacts the skin, eyes, or breathing passages. If skin
or eye irritation is noted, rinse the affected area with
plenty of cool, clean water. If breathing passages are
irritated, move to another area where there is plenty
of clean, fresh air to breath. If the irritation is not
alleviated by these actions, contact a physician.
REMOVAL
The following procedure is for replacement of a
faulty or damaged driver airbag. If the airbag is
faulty or damaged, but not deployed, review the rec-
ommended procedures for handling non-deployed
supplemental restraints. (Refer to 8 - ELECTRICAL/
RESTRAINTS - STANDARD PROCEDURE - HAN-
DLING NON-DEPLOYED SUPPLEMENTAL
RESTRAINTS). If the driver airbag has been
deployed, review the recommended procedures for
service after a supplemental restraint deployment
before removing the airbag from the vehicle. (Refer to
8 - ELECTRICAL/RESTRAINTS - STANDARD PRO-
CEDURE - SERVICE AFTER A SUPPLEMENTAL
RESTRAINT DEPLOYMENT).
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, FRONT IMPACT SENSOR,
SIDE IMPACT SENSOR, SIDE CURTAIN AIRBAG, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. DISCONNECT AND ISOLATE THE BAT-
TERY NEGATIVE (GROUND) CABLE, THEN WAIT
TWO MINUTES FOR THE SYSTEM CAPACITOR TO
DISCHARGE BEFORE PERFORMING FURTHER
DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE
WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
WARNING: WHEN REMOVING A DEPLOYED AIR-
BAG, RUBBER GLOVES, EYE PROTECTION, AND A
LONG-SLEEVED SHIRT SHOULD BE WORN. THERE
MAY BE DEPOSITS ON THE AIRBAG CUSHION AND
OTHER INTERIOR SURFACES. IN LARGE DOSES,
THESE DEPOSITS MAY CAUSE IRRITATION TO THE
SKIN AND EYES.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) From the underside of the steering wheel,
remove the two screws that secure the driver airbag
to the steering wheel armature (Fig. 19).
(3) Pull the driver airbag away from the steering
wheel far enough to access the three electrical con-
nections on the back of the airbag housing.
(4) Disconnect the steering wheel wire harness
connector for the horn switch from the horn switch
feed pigtail wire connector, which is located on the
back of the driver airbag housing.
WJRESTRAINTS 8O - 19
DRIVER AIRBAG (Continued)